Surround gate transistor and method for producing the same

ABSTRACT

A method for producing a semiconductor device includes depositing a first insulating film and a second insulating film on a planar semiconductor layer formed on a substrate; forming a first hole for forming a gate electrode in the second insulating film; filling the first hole with a first metal to form the gate electrode; forming a side wall formed of a third insulating film on an upper surface of the gate electrode and a side surface of the first hole; performing etching through, as a mask, the side wall formed of the third insulating film, to form a second hole in the gate electrode and the first insulating film; forming a gate insulating film on a side surface of the second hole; and epitaxially growing a semiconductor layer, within the second hole, on the planar semiconductor layer to form a first pillar-shaped semiconductor layer.

RELATED APPLICATIONS

The present application is a continuation of International Application PCT/JP2015/081495, with an international filing date of Nov. 9, 2015, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a semiconductor device.

2. Description of the Related Art

Semiconductor integrated circuits, in particular, integrated circuits including MOS transistors, have been produced with a continuous increase in the degree of integration. With this increase in the degree of integration, MOS transistors used in such integrated circuits have come to be produced with reduced dimensions on the order of nanometers. With such a reduction in the dimensions of MOS transistors, the leakage current is difficult to suppress; since a required amount of current needs to be ensured, a reduction in the area of circuits is difficult to achieve, which has been problematic. In order to address such a problem, a Surrounding Gate Transistor (SGT) has been proposed, which has a structure in which the source, the gate, and the drain are disposed in a direction perpendicular to the substrate, and the gate surrounds a pillar-shaped semiconductor layer (for example, Japanese Unexamined Patent Application Publication Nos. 2-71556, 2-188966, and 3-145761).

Forming a gate electrode after formation of the pillar-shaped semiconductor layer has been proposed (for example, Japanese Unexamined Patent Application Publication No. 2015-188115). However, when the pillar-shaped semiconductor layer is narrow, whether or not the pillar-shaped semiconductor layer can be formed so as to stand upright is not known.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a method for producing a semiconductor device in which a pillar-shaped semiconductor layer is formed after the gate electrode is formed, and the resultant semiconductor device.

A method for producing a semiconductor device according to an embodiment of the present invention includes depositing a first insulating film and a second insulating film on a planar semiconductor layer formed on a substrate; forming a first hole for forming a gate electrode in the second insulating film; filling the first hole with a first metal to form the gate electrode; forming a side wall formed of a third insulating film on an upper surface of the gate electrode and a side surface of the first hole; performing etching through, as a mask, the side wall formed of the third insulating film, to form a second hole in the gate electrode and the first insulating film; forming a gate insulating film on a side surface of the second hole; and epitaxially growing a semiconductor layer, within the second hole, on the planar semiconductor layer to form a first pillar-shaped semiconductor layer.

A semiconductor device according to an embodiment of the present invention includes a planar semiconductor layer formed on a substrate; a first pillar-shaped semiconductor layer formed on the planar semiconductor layer; a gate insulating film surrounding the first pillar-shaped semiconductor layer; a gate electrode surrounding the gate insulating film; and a first insulating film disposed between the gate electrode and the planar semiconductor layer so as to surround the gate insulating film.

The present invention can provide a method for producing a semiconductor device in which a pillar-shaped semiconductor layer is formed after the gate electrode is formed, and the resultant semiconductor device.

A method for producing a semiconductor device according to an embodiment includes depositing a first insulating film and a second insulating film on a planar semiconductor layer formed on a substrate; forming a first hole for forming a gate electrode in the second insulating film; filling the first hole with a first metal to form the gate electrode; forming a side wall formed of a third insulating film on an upper surface of the gate electrode and a side surface of the first hole; performing etching through, as a mask, the side wall formed of the third insulating film, to form a second hole in the gate electrode and the first insulating film; forming a gate insulating film on a side surface of the second hole; and epitaxially growing a semiconductor layer, within the second hole, on the planar semiconductor layer to form a first pillar-shaped semiconductor layer. In this way, after the gate electrode is formed, the pillar-shaped semiconductor layer can be formed.

In addition, before the first pillar-shaped semiconductor layer is epitaxially grown, the gate electrode formed of metal is covered by the first insulating film, the third insulating film, and the gate insulating film. As a result, metal contamination in the first pillar-shaped semiconductor layer can be suppressed.

In the structure including the first insulating film disposed between the gate electrode and the planar semiconductor layer so as to surround the gate insulating film, the first insulating film disposed under the gate electrode surrounds the gate insulating film. This structure ensures insulation between, at the lower end of the gate electrode, the gate electrode and the first pillar-shaped semiconductor layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a plan view relating to a method for producing a semiconductor device according to an embodiment of the present invention; and FIG. 1B is a sectional view taken along plane X-X′ in FIG. 1A.

FIG. 2A is a plan view relating to a method for producing a semiconductor device according to an embodiment of the present invention; and FIG. 2B is a sectional view taken along plane X-X′ in FIG. 2A.

FIG. 3A is a plan view relating to a method for producing a semiconductor device according to an embodiment of the present invention; and FIG. 3B is a sectional view taken along plane X-X′ in FIG. 3A.

FIG. 4A is a plan view relating to a method for producing a semiconductor device according to an embodiment of the present invention; and FIG. 4B is a sectional view taken along plane X-X′ in FIG. 4A.

FIG. 5A is a plan view relating to a method for producing a semiconductor device according to an embodiment of the present invention; and FIG. 5B is a sectional view taken along plane X-X′ in FIG. 5A.

FIG. 6A is a plan view relating to a method for producing a semiconductor device according to an embodiment of the present invention; and FIG. 6B is a sectional view taken along plane X-X′ in FIG. 6A.

FIG. 7A is a plan view relating to a method for producing a semiconductor device according to an embodiment of the present invention; and FIG. 7B is a sectional view taken along plane X-X′ in FIG. 7A.

FIG. 8A is a plan view relating to a method for producing a semiconductor device according to an embodiment of the present invention; and FIG. 8B is a sectional view taken along plane X-X′ in FIG. 8A.

FIG. 9A is a plan view relating to a method for producing a semiconductor device according to an embodiment of the present invention; and FIG. 9B is a sectional view taken along plane X-X′ in FIG. 9A.

FIG. 10A is a plan view relating to a method for producing a semiconductor device according to an embodiment of the present invention; and FIG. 10B is a sectional view taken along plane X-X′ in FIG. 10A.

FIG. 11A is a plan view of a semiconductor device according to an embodiment of the present invention; and FIG. 11B is a sectional view taken along plane X-X′ in FIG. 11A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a method for producing a semiconductor device according to an embodiment of the present invention will be described with reference to FIG. 1A to FIG. 11B. The semiconductor layer according to this embodiment is preferably a silicon layer. The semiconductor layer may be formed of another group IV semiconductor such as Ge or C. Alternatively, the semiconductor layer may be formed of a III-IV compound semiconductor.

As illustrated in FIGS. 1A and 1B, on a planar semiconductor layer 101 formed on a substrate 100, a first insulating film 102 and a second insulating film 103 are deposited; and, on the second insulating film 103, a resist 104 for forming a first hole for forming a gate electrode is formed. At this time, the resist 104 may be formed so as to have a first hole pattern for forming a gate electrode and a gate wiring. When the first hole pattern for forming a gate electrode and a gate wiring is formed, the width of the gate wiring is preferably set to twice or less the width of a side wall of a third insulating film described later. The diameter of the gate electrode is preferably set to twice or more the width of the side wall of the third insulating film described later. The first insulating film 102 is preferably a nitride film. The first insulating film may be formed as an oxide film. The second insulating film is preferably an oxide film. A diffusion layer may be formed in the upper portion of the planar semiconductor layer 101. An isolation insulating film 099 may be formed so as to surround the planar semiconductor layer 101.

As illustrated in FIGS. 2A and 2B, in the second insulating film 103, a first hole 105 for forming the gate electrode is formed.

As illustrated in FIGS. 3A and 3B, the resist 104 is removed.

As illustrated in FIGS. 4A and 4B, a first metal 106 is deposited in the first hole 105. The first metal 106 is preferably a metal used for semiconductor gates. The first metal 106 is preferably titanium nitride or aluminum titanium nitride.

As illustrated in FIGS. 5A and 5B, the first metal 106 is subjected to etch back, so that the first metal 106 is disposed within the first hole 105 and a gate electrode 106 a is formed. At the same time, a gate wiring 106 b may be formed.

As illustrated in FIGS. 6A and 6B, a third insulating film 107 is deposited on the upper surface of the gate electrode 106 a and the side surface of the first hole 105.

As illustrated in FIGS. 7A and 7B, the third insulating film 107 is etched so as to be left in a side-wall shape. Thus, a side wall formed of the third insulating film 107 is formed on the upper surface of the gate electrode 106 a and the side surface of the first hole 105.

As illustrated in FIGS. 8A and 8B, etching is performed through, as a mask, the side wall formed of the third insulating film 107 to form a second hole 108 in the gate electrode 106 a and the first insulating film 102.

As illustrated in FIGS. 9A and 9B, a gate insulating film 109 is deposited. The gate insulating film is preferably a high-dielectric-constant film. The gate insulating film preferably includes any one of an oxide film, a nitride film, and a high-dielectric-constant film.

As illustrated in FIGS. 10A and 10B, the gate insulating film 109 is etched to form a gate insulating film 109 on the side surface of the second hole 108. Before epitaxial growth of the first pillar-shaped semiconductor layer, the gate electrode 106 a and the gate wiring 106 b formed of the first metal 106 are covered by the first insulating film 102, the third insulating film 107, and the gate insulating film 109. As a result, metal contamination in the first pillar-shaped semiconductor layer can be suppressed.

As illustrated in FIGS. 11A and 11B, a semiconductor layer is epitaxially grown, within the second hole 108, on the planar semiconductor layer 101 to form a first pillar-shaped semiconductor layer 110. In this way, after the gate electrode is formed, the pillar-shaped semiconductor layer can be formed. Subsequently, a diffusion layer may be formed in the upper portion of the first pillar-shaped semiconductor layer.

The structure of a semiconductor device according to an embodiment of the present invention is illustrated in FIGS. 11A and 11B.

The semiconductor device includes a planar semiconductor layer 101 formed on a substrate 100; a first pillar-shaped semiconductor layer 110 formed on the planar semiconductor layer 101; a gate insulating film 109 surrounding the first pillar-shaped semiconductor layer 110; a gate electrode 106 a surrounding the gate insulating film 109; and a first insulating film 102 disposed between the gate electrode 106 a and the planar semiconductor layer 101 so as to surround the gate insulating film 109.

In the structure in which the first insulating film 102 is disposed between the gate electrode 106 a and the planar semiconductor layer 101 so as to surround the gate insulating film 109, the first insulating film 102 disposed under the gate electrode 106 a surrounds the gate insulating film 109. This structure ensures insulation between, at the lower end of the gate electrode 106 a, the gate electrode 106 a and the first pillar-shaped semiconductor layer 110.

The gate wiring 106 b may be connected to the gate electrode 106 a. An isolation insulating film 099 may be formed so as to surround the planar semiconductor layer 101.

Incidentally, the present invention encompasses various embodiments and modifications without departing from the broad spirit and scope of the present invention. The embodiments provided above are described for illustration of examples of the present invention, and do not limit the scope of the present invention.

For example, in the above-described example, the p-type (including a p^(+—)-type) and the n-type (including an n⁺-type) in the semiconductor device may be changed to the opposite conductivity types, and the resultant semiconductor device obviously falls within the technical scope of the present invention. 

What is claimed is:
 1. A semiconductor device comprising: a planar semiconductor layer on a substrate; an isolation insulating film surrounding the planar semiconductor layer; a first pillar-shaped semiconductor layer on the planar semiconductor layer; a gate insulating film surrounding the first pillar-shaped semiconductor layer; a gate electrode having a first sidewall surface surrounding the gate insulating film and in contact therewith; a gate wiring extending from the gate electrode in a lateral direction and having a same height as the gate electrode and a width in plan view that is less than a diameter of the gate electrode; a first insulating film between the gate electrode and the planar semiconductor layer and surrounding the gate insulating film; a second insulating film contacting a second sidewall surface of the gate electrode; and a third insulating film overlying the gate electrode and the gate wiring, and having a same planar shape as the gate electrode and the gate wiring. 